102 CARNEGIE INSTITUTION OF WASHINGTON. 



by these flowers of determining the number of stamens and o\Tiles 

 which they contain by making actual counts of both, resulting in finding 

 3,482 stamens and 1,980 ovules in one flower. 



The sahuaro was studied especially with reference to the cortical 

 ridges and the ribs of the fibro- vascular framework showing a numerical 

 correspondence. Both increase in number upward, so that they are 

 found to branch ascending the stem. The study of the method of 

 branching is still in progress. Externally the cortical ridges are some- 

 what closer together on the southerly half of the stem than on the 

 northerly half, and the same is true with reference to the fibro-vas- 

 cular ribs of the internal framework. The average of many measure- 

 ments showed that the ridges (and ribs) on the northerly and southerly 

 sides were numerically as 9 to 10^. 



In cross-section each fibro- vascular rib is ovate in outline, with the 

 smaller curve looking inward in the stem, the larger looking outward. 

 There are no visible growth-rings in the ribs, although they increase 

 in radial diameter. They show distinct medullary rays. Their more 

 detailed histology is still under investigation. 



Some Studies of Fouquieria splendens, by C. E. Bessey. 



Structural studies of this shrub were begun at the Desert Laboratory, 

 and continued at Lincoln, Nebraska. These included the flowers and 

 seeds, including germinations of the latter, and the growth of the young 

 seedling. These studies tend to confirm the suggestion that Fouquieria 

 should be taken from the order Caryophyllales, and included rather 

 in the order Ebenales, near the families Sj^mplocacese and Styracaceae. 

 Studies have been begun upon the structure of the cortex of the mature 

 stems, especially to the translucent layers overlying the chlorophyll- 

 bearing tissue of the cortex. 



Plant Succession, an Analysis of the Development of Vegetation, 

 by Frederic E. Clements. 



The summers of 1913 and 1914 have been spent chiefly in testing in 

 the field the conclusions as to the development of vegetation which have 

 been reached during the last decade in the study of Rocky Mountain 

 vegetation. The basic principles involved have been definitely formu- 

 lated during the past year, and an endeavor has been made to sum- 

 marize and correlate all of the literature which deals directly wdth plant 

 successions, amounting approximately to 500 titles. The vegetation 

 scrutinized during the two summers extends from the Great Plains to 

 the Pacific Coast and from the Canadian Rockies to the Mexican 

 boundary. The climax formations of this region have been traversed 

 repeatedly, and their variations and interrelations have been critically 

 compared. An attempt has also been made to coordinate the detailed 



